Railway block signaling apparatus



y 1959 s. w. FREEMAN 2,888,553

RAILWAY BLOCK SIGNALING APPARATUS Filed April 5. 1954 3 Sheets-Sheet l z 9 0 Lu 0) co m m 10 Z N RE O 3,

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INVENTOR. 1 .4 g 9 Y S.W.FREEMAN HIS ATTORNEY y 1959 s. w. FREEMAN 2,888,553

RAILWAY BLOCK SIGNALING APPARATUS Filed April 5, 1954 3 Sheets-Sheet 2 o m 2 9 i- O u; w A Q g :r nll \ll m 5 (D In w 00 HIS ATTORNEY May 26, 1959 s. w. FREEMAN 2,388,553

RAILWAY BLOCK SIGNALING APPARATUS Filed April 5, 1954 I 3 Sheets-Sheet 3 E l- E LO- E Q E E &

' INVENTOR.

BY S.W.FREEMAN E MMMJ HIS ATTORNEY Unit Sydney W. Freeman, Rochester, N.Y., assignor to General Railway Signal Company, Rochester, N.Y.

Application April 5, 1954, Serial No. 420,881

8 Claims. (Cl. 246-41) This invention relates to railway block signaling apparatus, and more particularly pertains to block signaling systems involving the use of track circuits.

Block. signaling systems usually employ track circuits to detect the presence of vehicles in the different blocks. These track circuits comprise a track relay connected across the track rails at one end of a track section or block together with a source of energy and a limiting resistor connected across the rails at the other end of the block. In this way, the track relay is normally energized so that when a train enters the block, the rails will be shunted and the track relay will be released.

This general organization has been found most useful and effective in the past; but, at the present time, trains of light weight are being operated at high speeds and under circumstances where such conventional track circuits may fail. In fact, many railroads are employing diesel-powered units which are relatively light; and in addition, such units are provided with automatic sanding apparatus which at times makes it almost impossible for the unit to be effective as a train-shunt and cause the release of the track relay for the block in which the unit is then located.

In View of the above and other important considerations, one purpose of the present invention is to provide a block signal system which employs the conventional track circuits for operation of the system in connection with the passage or" the usual type trains; but, in addition, it is organized to have apparatus which is distinctively responsive to the passage of the above mentioned light weight units travelling either alone or in various multiple combinations.

Another object of the present invention is to provide a track circuit organization with auxiliary apparatus to be distinctively responsive to the presence of a train in such a Way that it is operative to detect the presence of trains travelling in either direction.

A further object is to provide a train detecting system which is easily and economically combined with a block signaling system already employing intermittent inductive train control in such a way that the intermittent inductive train control apparatus can be in part employed as the auxiliary apparatus to be responsive to the special light weight cars or trains. In this connection, it is also desired to have this composite organization distinctively responsive to the light weight equipment alone.

Generally speaking, and without making any attempt to define the exact nature of the invention, it is proposed to provide a polarized track circuit in connection with the signalling system. This polarized track circuit is to employ a polar relay of the type which is responsive to only one polarity and which is reversibly connected to the track circuit. Similarly, the track source of energy at the other end of the track section is also reversibly connected to the track circuit.

The system is then provided with auxiliary apparatus at the entrance and exit of each track section which is distinctively responsive to the passage of the light weight tates Patent C F 2,888,553 C Patented May 26, 1.959

equipment. The entrance of a light weight unit into a section causes the track relay at that end to have its connections reversed (i.e. pole changed) with respect to the track circuit. This causes the track relay to release, i.e. operate to its biased position. When the light weight unit leaves the track section, it operates on the auxiliary apparatus to cause the track circuit source of energy to have its connections reversed (i.e. pole changed) with respect to the track rails. This causes energy to again be applied to the track circuit of a proper polarity to cause the track relay at the other end to again be operated. In this way, the passage of the light weight units successively reverses (i.e. pole changes) the connections of the track relay and track source of energy so as to ensure that the signals associated therewith are controlled to stop regardless of whether such unit is efiective to shunt the track circuit in the conventional way.

With an organization or" this general type, the fact that all trains of light weight or otherwise may act as a trainshunt is desirable even though the auxiliary equipment is employed. Since the regular trains do not efiect the auxiliary equipment, it is obvious that their train-shunt values are eiiective at all times to operate through the shunting of the track rails in the usual way.

Other objects, purposes and characteristic features of the present invention will in part be obvious from the accompanying drawings, and will in part be more specifically described hereinafter.

In describing the invention in detail, reference will be made to the accompanying drawings, in which like reference characters designate corresponding parts throughout the several views, and in which:

Fig. 1 is a diagrammatic view of a typical track section and the associated apparatus to constitute one block of a signaling system embodying the present invention;

Fig. 1A shows the wave form of a typical current impulse induced in a wayside inductor upon the passage of a car carried magnet;

Fig. 2 is a modified form of the invention shown in Fig. 1 adapted to employ line circuits and also organized in a manner to employ regular intermittent inductive train control equipment; and

Fig. 3 shows a mechanical form of train actuated device which is adaptable for use in place of the inductive ap- 'paratus shown in either of the prior forms.

For the purpose of simplifying the illustrations and facilitating in the explanation, the various parts and circuits constituting the embodiment of the invention have been shown diagrammatically and certain conventional illustrations have been employed, the drawings having been made more with the purpose of making it easy to understand the principles and mode of operation, than with the idea of illustrating the specific construction and arrangement of parts that would be employed in practice. Thus, the various relays and their contacts as well as the other devices are illustrated in a conventional symbolic manner.

The symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries, or other sources of direct current; and the circuits with which these symbols are used, always have current flowing in the same direction. The symbols (13+) and (B-) indicate connections to the opposite terminals of a suitable battery, or other direct current source, which has a center or intermediate tap designated (CN); and the circuits with which these symbols are used, may have current flowing in one direction or the other depending upon the particular terminal used in combination with the intermediate tap (CN). For the purpose of simplicity, the symbol (CN) may also be indicative of a common wire connection which may in aseaeas 3 this disclosure indicate an additional line wire for the control of the block signalling system.

With reference to Fig. 1, rails 5 and 6 of a stretch of track are divided into track sections A, B, C, etc. by suitable insulated joints 3. For example, track section B has associated therewith a signal 8 governing the entrance of trafiic into the section. A similar signal 9 governs the entrance of traffic into the next succeeding section. At the entrance to each track section is a suitable wayside inductor, such as inductors 10 and 11 for sections B and C respectively. Each inductor has associated therewith a suitable magnetic stick type relay, such as relay 8CK. The track section B associated with signal 8 is provided with a track relay 8TR which is connected through pole changing contacts 32 and 33 on the relay 8CK to the track rails 5 and 6. At the other end of the section B, a suitable track battery 8TB and limiting resistor 8LR are connected in series and through pole changing contacts 30 and 31 of the relay 9CK to the rails 5 and 6.

As above mentioned, the relays CG are of the magnetic stick type and may be of any suitable construction; but, for the purpose of definiteness in the disclosure, they may be of the type shown in the Hailes et a1, patent, No. 1,929,094, dated October 3, 1933.

The track relays TR are preferably of the biased to one position polarized type, i.e. their respective armatures operate in response to energization only by a particular polarity, while the other polarity merely acts to hold their armatures more firmly in their normal biased positions. One suitable relay of this type has been disclosed in the Willing et al. patent, No. 2,502,811, dated April 4, 1950. This relay will not respond to the wrong polarity even though greatly over-energized with such polarity.

Also associated with each track section is a suitable home relay, such as relay 8H for signal 8 governing trafiic over section B. These home relays are preferably of the retained neutral type, so that they will not release their neutral armatures upon a quick reversal of their polarity of energization. One suitable relay of this type is disclosed in the Willing et al. patent, No. 2,486,086, dated October 25, 1949. This type of retained neutral relay is preferable so as to prevent a shift in the polarity behind a train from causing a momentary dropping away of the relay armature, and thus cause a cascading of a momentary reversal of polarity through the successive blocks to the rear of that train.

More specifically, relay 8H is normally energized with a positive polarity from (3+), and over a circuit including front contact 15 of relay 9H, line Wire 16, front contact 17 of relay STR, windings of relay 81-1, to the common return line designated by the symbol (CN). While the relay 81-1 is thus energized, its neutral contacts 18 and 19 are picked up and its polar contact 20 is actuated to a left-hand position. Thus, the green lamp G of signal 8 is energized through a circuit closed from and including front contact 19 of relay 8H, polar contact 20 of relay 8H in a lefthand position, lamp G of signal 8, to if the line circuit including line wire 16 were energized by the opposite polarity with contact 15 of relay 91-1 in a released position, then the polar contact 20 of relay 8H would be actuated to a right-hand position in which the yellow lamp Y of signal 8 would be energized through an obvious circuit also including front contact 19. In the event a train is in the track section including rails 5 and 6, or for any other reason that the track relay 8TR is dropped away opening front contact 17, the relay 8H is deenergized causing its contacts 18 and 19 to assume dropped away positions. With contact 19 in a released position an obvious circuit is closed for the red lamp R of signal 8.

With the organization just described, the passage of a train of the conventional type into the track section B,

4 causes the rails 5 and 6 to be shunted which reduces the interrail potential to a value below which the track relay 8TR will remain picked up. This releasing of the track relay 8TR opens contact 17 and causes relay 8H to be released which in turn causes the signal 8 to have its red lamp R energized to display a stop signal aspect. As the train passes through the section B this condition is maintained. Obviously this shunting of the track rails 5 and 6 causes increased current flow from the battery 8TB, but such increased current flow is limited by the limiting resistor ELR to some feasible value. As this train passes into the next track section C, the track relay 9TR is deenergized causing the signal 9 to be placed at stop by reason of the deenergization of the relay 9H. But when this train wholly enters this track section C, then negative potential is applied to the relay 8H because the relay 81R becomes picked up through its track circuit in the usual Way. This causes the signal 8 to give a caution aspect by the energization of its yellow lamp Y.

When the train passes into the second track section in advance of section B, the relay 9H is picked up so that positive potential is applied to the relay 8H and its picking up again causes signal 8 to display a green indication by the energization of its green lamp G.

In this way, a conventional train passes through the various track sections and controls the block signaling in the regular Way.

Let us assume that a car or train of light weight equipment is to pass through the section. Such a train or car carries a transmitting device 22. which may be either an electromagnet strongly energized or may be a permanent magnet of a rather highly magnetized type. This car carried device 22 is preferably attached to the forward end of the train, but in the case of a single light weight unit, it may be attached to either end of such unit.

As this magnet 22 passes over the wayside inductor 10, currents are induced in the winding 12 of the wayside inductor which are supplied to the relay 8CK. These induced currents have a peculiar wave shape typically illustrated in Fig. 1A, for example. Obviously, the amplitude of the induced current will depend upon the speed of movement of the car carried device 22 relative to the wayside inductor as well as its intensity of magnetization. However, as the magnet approaches the leading end of the inductor, a positive Wave 24 of relatively small value is induced in the winding 12. As the magnet 22 passes directly over the wayside inductor 10, a negative wave 25 of much greater magnitude is induced. As the magnet 22 passes over the trailing end of the wayside inductor, another positive Wave 26 of relatively small value is produced.

The Winding 12 and the impedance of the windings of the relay SCK are so selected that these positive currents 24 and 26 are of insuficient magnitude to actuate the relay, but the magnitude of the negative current Wave 25 is effective to actuate the relay. in this connection, it should be noted that the upper winding of relay SCK is the pick-up winding of the relay while the lower winding is the knock-down winding. This has been indicated in the drawings by the arrows within the relay symbol. Thus, when. a negative pulse of the proper relative magnitude as above described flows through the upper Winding of relay 8Ci l as selected by contact 28, the contacts of this relay SCK are picked up and remain picked up because of the magnetic stick characteristics of the relay. On the other hand, when a negative pulse of the proper relative magnitude flows through the lower Winding of relay ECK, as selected by contact 28, the contacts of this relay are dropped away and remain dropped away because of the magnetic stick type characteristics of the relay.

It is noted that each operating pulse of energy for the relay SCK is broken through contact 28, but the pulse '5 of" energy due to a moving train is "of" relatively short duration. For example, the duration of a pulse of current for a train traveling at sixty miles per hour may be in the order of two hundredths of a second, but if the train is traveling at ten miles per hour, the pulse may he in'the order of one tenth of a second. These impulses are suflicient to actuate the relay but are not effective on the other winding when the contact has moved to its. new position. This is because the response and the transit time of the contacts is such that the closure of contact 28 in the new position does not allow sufficient energization of the other winding of this relay .SCK to effect an operation of the contacts.

As shown in Fig. 1, the upper rail is positive because contacts 30 and 31 of relay 9CK are in released positions, so that current is flowing through back con-. tacts 32 and 33 of relay SCK in a proper direction to energize the track relay STR and cause its contacts to be. picked up.. However, the actuation of the relay tiCK by the passage of the magnet 22 over the inductor 10, causes the contacts 32 and 33 to pole change the connection of track relay 8TR to the track rails. Thus, the potential then-applied to the track relay 8TR is in an opposite direction. This causes its contacts to release and open front contact 17. In this way, this car passing through the section B is efiective to hold the signal 8 at stop regardless of whether or not its Wheels actually shunt the track rails 5 and 6 to a sufiicient degree to maintain a track relay STR released.

When the car passes the inductor 11, the magnet device 22 causes inductive eflfect the same as explained in connection with the inductor 10. The negative impulse thus produced actuates the relay 9CK so that its contacts pick up in which positions they remain until another impulse is supplied to them. This operation of contacts 30 and 31 pole changes the connection of track battery 8TB to the rails 5 and 6 which isrnow again in correspondence with the polarity required for actuating the track relay STR. Thus, assuming that the train has passed out of the section B, the current flows through the rails to pick up relay STR. This allows the relay 8H to be energized with negative polarity the same as if a regular train had passed through the section B.

The next successive light weight equipment car causes a current of negative characteristics to be induced in the winding 12 which in passing through the lower winding of relay 80K causes its contacts to be knocked down or restored to their positions shown. Again this pole changes the connections of the track relay STR so that it releases. But when the train has passed through the section and supplies an inductive pulse to the relay 9CK, it is also knocked down or released and its contacts 30 and 31 again pole change the connections for track battery TB to the rails 5 and 6. This allows the track relay 8TR to again pick up.

In brief, each track section operates in the way of a conventional track circuit except that in addition to the normal shunting characteristics of a train, the track circuit connections are reversed upon the entrance of a train and are again reversed upon the exit of a train. When one reversal has taken place, regardless of the direction of the train, the track relay is released; but when two reversals have taken place to establish the original corresponding connections, regardless of the direction of the train, the track relay is maintained energized over the track circuit in the usual way.

Modification of Fig. 2

the track sections is provided with similar apparatusso that a description of the apparatus associated with section B will be typical of each of the other sections; More specifically, the section B is provided at one end with 'a track relay 8T directly connected across the rails 5 and 6, which relay may be any suitable neutraltype relay. At the other end of the section, the track battery 8TB is connected in series with the limiting resistor 8LR directly across the track rails 5 and 6.

Signal f the color light type is shown as governing trailic over the track section B; while a similar signal 9 is shown as governing trafiic over the section C.

Each of the signal locations is provided with a home relay, such as relays 8H and 9H. These home relays are preferably of the retained neutral type for reasons previously explained in connection with Fig. 1; and the structure of these relays may be of the type disclosed in the prior mentioned Willing et al. Patent No. 2,486,086, dated October 25, 1949. Each of thehorne relays is normally energized. For example, the relay SH is normally energized from (B-l), through a circuit including front contact 15 of relay 9H, over line wire 16, front contact 449 of track relay 8T, front contact 41 of line relay 8L, windings of relay 8H, to the common return wire indicated by the symbol (CN).

Each signal location is also provided with a line relay such as relay 8L, a line battery such as battery 8LB, a control relay such as 8CK, a pulse relays such as relay 8P, and two control relays such as SCI. and 8CH. Also, in advance of each signal is a suitable wayside inductor such as the inductor 10, previously described in connection with Fig. l.

The line relays such as relay 8L are preferably of the polar biased type the same as described in connection with the track relays TR of Fig. 1. Thus, these relays may be so constructed as to be normally biased toone position and actuated to the opposite position only in response to energization by a particular polarity. Although this type of relay may take many difierent forms, one such relay has been disclosed in the Willing et al. patent, No. 2,520,811, dated April 4, 1950.

The relays, such as SCK, are preferably of the magnetic stick type, such as shown for example in the Hailes et al. Patent No. 1,929,094, dated October 3, 1933.

The relays SCH and SCI. are regular neutral relays, but their windings have relatively high or low impedances of values selected in accordance with the principles of, the invention as later explained. Rectifier units 60 and 61 are associated with relay 8CL so as to make it responsive to current flow in either direction. Similar rectifier units 62 and 63 are associated with relay SCH for the same reason. The relay SP, for example, is a regular neutral relay but with releasing characteristics only suficiently slow as to allow time for the operationof the associated relay SCK.

Each of the line relays L is normally energized. For

7 example, the line relay SL is normally energized from the positive terminal of line battery 8LB overa circuit including back contact 42 of relay 9CK, line wire 43, front contact 44 of track relay 8T, back contact 45 of relay SCK, windings 0f relay 8L, back contact 46 of relay SCK, front contact 47 of track relay 8T, line wire 48, back contact 49 of relay K, to the negative terminal of the line battery 8LB. In this way, the line relay SL is normally energized and operated so long as the respective pairs of contacts 45-46 and 42-49 are in correspondence; but, the line relay SL is dropped away when the polarity of current is opposite to that to which the relay 8L will respond.

It will be observed that the pulse relays, such as relay 8P are normally energized. For example, relay SP is energized from through a circuit including back contact 50 of relay 80L, back contact 51 of relay 8CH, windings of relay 8P, to

Each wayside inductor is organized to cooperate with the receivers on the passing trains in a manner of an intermittent inductive train control system, such as shown.

aeaasss and described for example in the prior patent to C. S. Bushnell, Pat. No. 1,686,434, dated October 2, 1928. An intermittent inductive train control system as shown in the above mentioned patent includes a car carried receiver with primary and secondary windings which receiver is adapted to cooperate with the wayside inductors along the trackway. The primary winding of each receiver is normally energized to a proper degree so that when the receiver passes over a wayside inductor which has its winding open circuited, the magnetic flux from the primary winding will pass through the secondary Winding on the receiver to a sufiicient degree to cause the release of a car carried relay which is effective to give the desired train controlling functions. The wayside inductor is thus open circuited when the associated signal is at caution or stop.

On the other hand, if the wayside inductor has its winding short circuited, then the passage of a receiver over the inductor does not permit sufilcient magnetic flux to pass from the primary winding through the inductor and thr ugh the secondary winding to cause a relay controlling effect on the car. This is the condition to which the Wayside inductor is controlled when the associated signal is clear.

In brief, the train controlling effect is transmitted to the car carried receiver dependent upon whether the winding on the wayside inductor is closed or open. In one such train control system that has been widely used in actual practice, it has been found that when the wayside inductor has its winding short circuited through any resistance below four ohms, the wayside inductor has no effect on the car carried apparatus the same as if the winding were actually short circuited. It has also been found that if the winding on the wayside inductor is connected to a resistance of any value over twelve ohms, the efiect of the wayside inductor on the car carried receiver is substantially the same as if the Winding of the wayside inductor is wholly open circuited. With these general observations in mind, the organization and operation of the present invention as disclosed in Fig. 2 will now be discussed in greater detail.

It is assumed that all of the trains operating over the stretch of track illustrated in Fig. 2 are provided with train control apparatus of the type generally described above; and that those trains which include light weight equipment or are constituted by single light weight powered units, have in addition to the train control receiver a transmitting device which is substantially the same as the receiver above mentioned except that its core structure is provided with a single winding which is normally energized to a much higher degree than the primary Winding of the car carried train control receiver. It is, of course, to be understood that this car carried transmitter may be a permanent magnet such as described in Fig. 1 providing, of course, that the density of its magnetization is substantially greater than the magnetization provided by the primary winding of the car carried receiver.

Since the operation of the system disclosed in Fig. 2 is substantially the same as Fig. 1 upon the passage of a car or train having only the train control equipment, this operation will not be described in detail in connection with Fig. 2. It is sufficient to know that such train provides an adequate train-shunt for each track section which it occupies and causes the release of the track relay for that section. For example, the presence of a train in section B causes the release of track relay 8T opening front contact 40 to release the home relay 8H. Also, the opening of contacts 44 and 47 releases the line relay 8L which in turn opens contact 41. The relay 8H controls the signals in the usual way and acts through its contact 58 to control the wayside inductor as will be presently described. In other words, the interaction of the train control equipment and the wayside inductor is the same for all kinds of trains so that its description ca with respect to a. light weight train will be sufiicient for an understanding of the organization.

For the purpose of this disclosure, the light weight train is assumed to have a car carried transmitter 52 which has a winding 53 normally energized from a battery or other source of direct current 54. In this connection, it should be understood that suitable added apparatus may be provided, if desired, to provide an indication on the train that this energization of the transmitting device is continuously effective.

Associated with the transmitter and preferably located on the car in front of the transmitter a suitable distance, is the car carried train control receiver 55 which has a primary winding 56 and a secondary winding 57. The primary winding is normally energized and both the primary and secondary windings are connected to suitable train control apparatus such as shown and described in the above mentioned Patent No. 1,686,434.

It should be noted that the windings of the relay 8CH provide a relatively high resistance so that the connection of this relay across the winding 12 of the inductor I!) is the same as if the winding 12 were open circuited insorar as its effect on the train control receiver is concerned. Likewise, the windings of the relay SCL are of a value which, when connected across the windings 12, provide the same effect on the train carried receiver as if the winding 12 were short circuited. In other words, there is sufficient shunting of the winding 12 on the wayside inductor 10 as to block ofi the flow of flux through the receiver 55 as it passes over the inductor to prevent the release of the car carried relay and the automatic operation of the train control equipment. In brief, when contact 58 of relay 8H is closed, the wayside inductor 10 gives a clear controlling effect for the car carried receiver 55; but when the front contact 58 is open, which it will be when the signal 8 indicates either caution or stop, the controlling effect of the inductor It on the receiver 55 is the same as if the winding 12 were open circuited and causes a stop controlling effect to be set up by train controlling equipment.

As above mentioned, it is assumed that the receiver 55 is located on the car in advance of the transmitter so that this operation of the train control equipment will be in accordance with the trafiic conditions on the trackway in advance of the train and before the transmitter can act to register the presence of this train in advance of the signal 8. Also, the above explanation discusses the effect on the car carried equipment which is provided by the wayside inductor. It should be noted that the degree of energization of the primary winding 56 on the car carried receiver 55 is insufiicient to cause an induced current in the winding 12 that will aifect the operation of either of the relays 8CL and 8CH.

Now let us assume that this car has passed the inductor 10 to the point where the transmitter 52 passes over the inductor 10. The current impulse induced in the winding 12 is the same as explained in connection with Fig. 1 and graphically illustrated in Fig. 1A. However, both of the relays 8CL and SCH are provided with their associated rectifier units so that the complete induced current wave forms may be effective to act on the associated relay then selected by the position of the contact 58.

Let us assume that the light weight equipment train is travelling on clear signals with no other trains immediately in advance. Under these circumstances, the front contact 58 is closed so that the impulse induced in the winding 12 upon the passage of the transmitter 52 flows through the upper and lower windings of relay BCL and through front contact 58. Since the rectifiers 6t) and 61 are employed, the positive portions will pass through one winding and the negative portions will pass through the other winding. This impulse is of suflicient magnitude to cause the relay to operate its contacts. Before considering the result of this operation of relay 801., it should be noted that its energization is in multiple with the relay 8CH which has sufiiciently high resistance values as to allow a relatively small proportion of the impulse to pass through its windings, and in any event this small proportion of the energy is not effective to actuate the contacts of relay SCH.

The picking up of contact 50 of relay 8CL opens its back contact 50 to deenergize the pulse relay SP and to close its front contact 50 to supply energy to the upper winding of relay SCK through front contact 64 and back contact 65. I The energy which flows in this circuit for the upper winding of connector relay SCK is continued only during the release period of the relay 8P. This is sufficient to cause the actuation of the contacts of the relay SCK, but the energy is cut off before the contacts of the relay SCK are able to close their front points and allow this energy to be elfective in its lower winding. In this way, a single pulse of energy is applied to the relay 8CK to actuate it to its picked up position. This takes place regardless of whether the relay 8CL is picked up for a long or a short time dependent upon the speed of passage of the train. It should be noted in this connection that this same cutting off of the energy by the relay 8? would be effective if the relay 8CK were in a picked up position and were being knocked down by energization of its lower winding.

This actuation of the contacts of connector relay SCK shifts or'pole changes the connection of the relay 8L with respect to the line wires 43 and 48 by reason of the operation of contacts 45 and 46. Since the new polarity is wrong for the operation of the relay 8L, its contact 41 drops away and deenergizes the relay 8H to place the signal 8 at stop registering the presence of the train in the track section B regardless of whether or not its wheels and axles act as a train-shunt to cause the release of the track relay 8T.

When the train passes the inductor 11, a similar operation occurs as just explained in connection with the passage of the train past inductor 10. Omitting the detail operations, it will be noted that the relay SCK has its contacts picked up which causes contacts 42 and 49 to shift or pole change the battery SLB with respect to the line wires 43 and 48: Since the train is registering itself out of the block, it is proper for this new polarity to affect the energization and operation of the line relay 8L to restore the closure of front contact 41 and to allow relay 8H to be energized in accordance with the position of relay 9H. Since the picking up of the relay 9CK in this instance causes the release of relay 9L, the relay 9H will, of course, be released during the presence of the train in the section C. In this way, the train can pass from section to section registering its presence in each section in turn by reason of the effect of its transmitter on the wayside inductors. It should be noted that this is in addition to any shunting effect that it may have on the track relays of the respective sections.

There may be instances when the section B, for example, is occupied by a conventional train and by reason of its shunting the track rails causes the track relay 8T to be dropped away and-in turn the relay 8H. At such time, a light weight equipment train may approach the signal 8 while it is displaying a stop aspect. This light weight equipment train must first stop to acknowledge the stop signal, and then it may proceed past signal 8 prepared to stop short of an obstruction in accordance with railroad rules. In this instance, front contact 58 is open and the passage of the light weight equipment train will first have its car carried receiver 55 acted upon by the inductor 10 the same as if the winding 12 were open circuited, because the impedance of the windings of relay 8CH are above the critical value. But when the transmitter 52 passes over the wayside inductor 10, its high degree of energization is efiective to produce a current impulse in the winding 12 of a wave. shape such as shown in Fig. 1A, which impulse because of the associated rectifier units 62 and 63 is 10 effective in its entirety to act upon this relay SCH. The picking up of the contact 51 of relay SCH acts to release the relay SP and to close a circuit through front contact 51 for acting upon the relay 8CK in the same way as explained in connection with the relay 8CL. In other words, the relay 8CK is shifted to a new position to register the passage of this train into the section B. This happens even though the section B may be occupied as indicated by the deenergized condition of the relay 8H.

Assuming that the conventional train (i.e. the train preceding the light weight equipment train) continues through the section B and leaves it, then the light Weight equipment train continues through the section B and may enter the section C subject of course to the indications of signal 9. When the light weight equipment train passes the inductor 11, it acts on the relay 9CK the same as explained in detail in connection with the relay SCK, and is thus registered out of section B and into section C. In this way, the system handles the situation of double occupancy of a block with all of the usual track circuit safe guards with the additional control provided for the light weight equipment cars.

There is another situation in which double occupancy of a block may take place; and this is when both the first and the second trains are of the light weight equipment type. Obviously, these trains must obey the signal aspects, and the second train may enter the block only after stopping for the stop signal and then proceeding prepared to stop short of an obstruction as provided in accordance with the usual railroad rules.

More specifically, let us assume that a first train of the light weight equipment type enters the section B and registers itself into the section by the operation of relay 8CK as previously described. Since it has not registered itself'out of the section, the contacts of the relay 8CK and the relay 9CK are out-of-correspondence. The entrance of the second train into this section, if it were a light weight equipment type train, would actuate the contacts of the relay 8CK and bring them into correspondence with the contacts of relay K. This would allow for the energization and operation of the relay 8L (see Fig. 2) insofar as the auxiliary equipment is concerned. However, it has been found in practice that when these light weight units are employed in multiple, they are effective as train-shunts and for this reason the track relay 8TR would be deenergized and the relay 8H would be maintained released. Also, the relay 8L would remain deenergized because of open contacts 44 and 47. As soon as the first light weight train leaves the track sectionB, the relay 9CK is operated so that it is out-of-correspondence with the relay SCK while only the single unitremains in the section B. In this way, all single unit light weight equipment trains are assured of adequate protection by the auxiliary equipment while they are operating as single units, but when two such trains are in the same track section, they are afforded the usual track circuit protection.

In this form of the invention shown in Fig. 2, two relays SCL and SCH are shown with their respective rectifier units. This particular embodiment is provided so that full advantage may be taken of the complete impulse; but if it is desired to use only a particular portion of the wave form, the high and low windings may be placed on a single relay structure with suitable rectifier units to allow the flow of only a particular polarity. Insofar as the operation of the relays SP and SCK are concerned, the result is exactly the same. However, it is thought that the form shown in Fig. 2 is more eflicient, whereas this combining of the function of the two relays is perhaps the more economic one. In either case, the reception of an impulse of the proper magnitude as provided by the highly energized transmitter 52 on a train causes the actuation of the associated relay CK.

Also, Fig. 2 illustrates the use of line wires, but it should be understood that the relays L maybe controlled over the track rails and 6 the same as shown in Fig. 1, if desired, so as to reduce the amount of equipment involved. In other words, the features provided in this form of the invention shown in Fig. 2 with regard to the joint use of the impulse apparatus for train control and train presence registry, may be applied to the form of the invention shown in Fig. 1 where the track rails and the track circuit conditions are used as a part of the communication of train presence.

In the above description, it has been pointed out how the relays 8CL and 8CH, for example, have the proper impedances to permit the selective control of the wayside inductor 10 by contact 58 to accomplish the desired train control elfect on the receiver 55. It has also been pointed out that this receiver 55 does not in turn cause the operation of these relays 8CL and SCI-I, but rather that a more highly magnetized car carried element, such as transmitter 52, is required to cause the operation of these relays.

However, it should be understood that, if desired, all trains may actuate the auxiliary train detecting apparatus. In such a case, the relays 8CL and SCH may be so designed as to act in response to the currents induced in the wayside inductor 10 by the passage of the receiver 55. In other words, the primary winding 56 of such a car carried receiver 55 is always energized causing the device to be continuously magnetized so that its passage over the wayside inductor 10 does cause some current flow in the winding 12; and for the purposes here considered, the relays SCL and SCH may be designed to respond to these currents. Thus, the added car carried transmitter 52 is not required. In this contemplated possible modification, it is assumed that there is no desire to distinguish between the regular trains and those composed of light weight equipment. This form has not been shown in the drawings since it is merely a matter of proper design of the sensitivity of the relays 8CL and 8CI-I together with the omission of the car carried transmitter 52.

Modification of Fig. 3

It should be understood that the invention is adaptable to railroads that desire to use some form of track instrument rather than an inductive device such as described in connection with Figs. 1 and 2. Although such a mechanical wayside device might take numerous forms, it is believed sufiicient for the present disclosure to show one form such a device might take.

With reference to Fig. 3, a trackway device is constructed to have a base plate 80 upon which is mounted a four-sided wheel 81 which has suitable slots 82 at each of its four corners. These slots are adapted to receive an operating finger 83 of a car carried device 04. This device 84 is provided with flat surfaces 85 which may pass over the fiat surfaces of the wheel 81 and in fact they are assumed to travel in a plane relatively close to the wheel 31 so as to prevent its rotation while these surfaces are over it. But the device 84 is provided with a recess 86 adjacent the operating finger 83 so that as this finger is received by one of the slots 82, the wheel 81 can be rotated 90 and is then held by the trailing fiat surface 85 of the car carried device 84. In this way, the passage of a car having the device 84 mounted thereon can operate the wheel 81 only through a 90 movement.

A suitable shaft is extended from the wheel 81 to a contact box or housing which includes a cam 87 which has recesses 80 for receiving a suitable detent 89 for holding the wheel 81 in its diiferent positions between the successive passages of trains carrying the operators 33. At the end of the shaft is a cam 90 which actuates two plungers 91 and 92. When the cam 90 is in the position shown the associated contacts 101, 102, 103 and 1104 take the positions shown; but when the cam 90 has been operated to the next 90 position the plungers 91 and 92 are operated outwardly to cause these contacts 101, 102, 103 and 104 to take their opposite positions. On the next succeeding operation, the cam again assumes a position similar to that shown after having travelled another 90". Thus, the contacts 101, 102, 103 and 104 are restored to the positions shown. In this way, the contacts are operated to opposite positions for the passage of each successive train.

It should be noted that these contacts 103 and 104 may be connected as shown and then to the track rails the same as shown in Fig. 1. This would provide exactly the same operation for the track relay STR as that described in connection with Fig. 1. The track battery 7TB and a limiting resistor 7LR would be connected through contacts 101 and 102 to the track rails 5 and 6 of section A. In this Way, the battery connections would be reversed upon each successive passage of a train. It is believed unnecessary to show the connections in detail, since the organization and operation are so closely analogous to that described in connection with Fig. I.

It will be observed that this form of the invention may be used in connection with hand cars and motor cars on the railroads. At the present time, such motor cars used by the track maintenance crews are protected merely by reason of their obtaining clearances through a dispatcher. The present invention in the form of Fig. 3 could be readily applied to any block signalling system with very little added equipment and in such a way as to give adequate protection to the hand cars and/or motor cars even though such vehicles have insulated axles and do not shunt the track rails. This is pointed out to indicate the versatility and difierent fields of usefulness of the present invention in connection with block signalling systems.

Having thus described several forms of the present invention, it is desired to be understood that these forms are selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume; and, it is to be further understood that various modifications, adaptations and alterations may be applied to the specific form shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention.

What I claim is:

1. In combination with a stretch of railway track, a biased to one position polarized relay located at one point along said stretch of track, a source of energy located at a remote point along said stretch of track, circuit means extending between said two points, a twoposition connector relay for reversibly connecting said polarized relay to said circuit means at said one point, another two-position connector relay for reversibly connecting said source of energy to said circuit means at said remote point, and means located at each of said points along said stretch distinctively influenced by train carried apparatus for actuating said two-position connector relay at the corresponding point to its opposite position to thereby cause the contacts of said polarized relay to assume their biased positions when a train enters the section and to be operated to their opposite positions when the train leaves the section.

2. In combination with a section of railway track, a track circuit for said section including a source of current at one end or" said section, a polar biased track relay at the other end of said section, circuit connector means at said one end for reversibly connecting said source to said track rails, separate circuit connector means at the other end of said section for reversibly connecting said polarized track relay to said rails, and means.

at each end of said section responsive to the passage of train carried inductive means to actuate its associated circuit connector means to effect a reversal of its as sociated circuit connections, whereby the actuation of one of said circuit connector means results in the release of said track relay and the actuation of both of 13 said circuit connector means results in the operation of said track relay.

3. In combination with the track rails of a section of railway track, a track circuit for said section including a source of current and a limiting resistor connected in series at one end, a polar biased track relay at the other end, a first connector for reversibly connecting said source of current and limiting resistor to the rails of said section at its end, a second connector at the other end of said section for reversibly connecting said track relay to the rails of said section at that end, inductive means located adjacent each end of said section and respectively influenced by inductive means carried by a train to actuate the associated first or second connector each time a train enters said section and each time a train leaves said section, whereby the'entrance of a train in said section results in the release of said polarized track relay regardless of whether such train is an efiective train shunt.

4. In combination with the track rails of a section of railway track, said section being insulated from adjoining sections to constitute a track circuit including a source of current and a limiting resistor connected in series across the rails at the exit end of said section and a track relay connected across the track rails at the other end of said section, a signal for governing traflic over said section, a biased to one position polarized relay located at the entrance end of said section, a source of energy located at the exit end of said section, line circuit means extending between the entrance and exit ends of said section and including front contacts of said track relay, a two-position connector relay at the entrance end of said section for reversibly connecting said polarized line relay to said line circuit at that end, another two-position connector relay located at the exit end of said section for reversibly connecting said source of energy to said line circuit at that end, means located at the entrance end of said section and distinctively influenced by the passage of a train for actuating the associated two-position connector relay to thereby reverse the connections of said line relay to said line wires, means located at the exit end of said section and distinctively influenced by the passage of a train having train carried inductive means for actuating the associated two-position connector relay to an opposite position to thereby reverse the connection of said source to said line wires, and wayside circuit means for controlling said signal said circuit means being jointly controlled by said polarized line relay and said track relay.

5. In combination with the track rails of a section of railway track, a signal for governing traflic over said section of track, a track circuit for said section including a source of current and a limiting resistor connected in series at the exit end of said section, a polar biased track relay at the entrance end of said section, a two-position device at the entrance end of said section for reversibly connecting said track relay to the rails of said section at its end, another two-position device at the exit end of said section for reversibly connecting said source of current and limiting resistor to the rails of said section at said exit end, inductive means located adjacent the entrance end of said section and influenced by inductive means carried by a train to actuate the associated twoposition device to a different position each time a train enters said section, inductive means adjacent the exit end of said section influenced by inductive means carried by a train to actuate the associated two-position device at said exit end to a difierent position each time a train leaves said section, and wayside circuit means controlled by said polar biased track relay at the entrance end and in accordance with trafiic conditions in the next section in advance for controlling said signal governing the entrance of traflic into said section, whereby said signal is jointly controlled upon the entrance of a train into said section by its train-shunt efiect and by its inductive efiect upon the inductive means adjacent the entrance and exit ends of said section.

6. In combination with the track rails of a section of railway track, a signal for governing traflic over said section, a track circuit for said section including a source of current and a limiting resistor connected in series across the track rails at one end, a track relay connected across the track rails at the other end, a polar biased relay located at the entrance end and a source of energy located at the exit end, line circuit means extending between said entrance and exit ends of said section, a twoposition connector relay for reversibly connecting said polarized relay to said line circuit means at said entrance point, another two-position connector relay for reversibly connecting said source of energy to said line circuit means at said exit end, a wayside inductor located just in advance of said signal, wayside signaling apparatus controlled in accordance with traflic conditions including control by said line relay and said track relay, said wayside signaling means also providing a circuit for said wayside inductor only when said signal is controlled to indicate clear, and relay means selectively included in the circuit means for said wayside inductor unresponsive to the wayside control by said signal control means but being actuated upon the passage of a highly energized transmitter located on a passing train, and circuit means for actuating the associated two-position connector relay each time a highly energized transmitter passes said wayside inductor.

7. In a railway signaling system having a track section, a track circuit for said track section including a source of energy connected across the track rails at one end of the track section and a biased to one position polarized track relay connected across the track rails at the other end, pole changing means at each end of the track section operable When rendered effective to pole change the connection of the polarized relay across the track rails, pole changing means at the other end of the track section operable when rendered efiective to pole change the connection of the source of energy across the track rails, and means at each end of the track section responsive inductively to car carried inductive equipment for rendering said pole changing means efiective at the associated end of the track section.

8. The combination with a railway track section of a track circut for said track section including a source of energy connected across the track rails at one end of the track section and a magnetic stick track relay connected across the track rails at the other end, pole changing means at each end of the track section eflective when actuated to pole change the connection of the polarized relay across the track rails, pole changing means at the other end of the track section eifective when actuated to pole change the connection of the source of energy across the track rails, a wayside inductor at each end of the track section having a winding, circuit means for selectively applying a relatively high or low impedance shunt across said winding, said circuit means including electroresponsive means that is responsive to an induced voltage in said winding irrespective of whether said relatively high or low impedance shunt is efiective, and circuit means at each end of the track section for actuating said pole changing means at the associated end in accordance with the response of said electroresponsive means at the associated end of the track section to a voltage induced in said inductor when a train having car carried inductive means passes through said section:

References Cited in the file of this patent UNITED STATES PATENTS 1,845,175 Padmore Feb. 16, 1932 2,032,810 OMeara Mar. 3, 1936 2,102,445 Vanhorn Dec. 14, 1937' 2,360,948 Jerome Oct. 24, 1944 

